1. Field of the Invention
This invention relates to hinges for doors or windows and more particularly to lockable butt hinges for household doors.
2. Summary of the Prior Art
Lockable hinges have been known for a long time and are described as far back as 1889 in Canadian Pat. No. 31895. Such lockable hinges have usually been considered in relation to shutters and the like and have been concerned primarily with an arrangement whereby the shutter or door is in a fully closed or fully open position.
With the usual household front entry door, in terms of personal safety there is a practice of providing a short safety chain so that a person inside the house may open the door a short distance with the chain attached to see who is outside. The short chain is intended to prevent access by an undesirable person after the door has been partially opened.
In terms of allowing for ventilation of a household, it may also be desirable to have a front door open to different degrees of opening anywhere between being open only a slight crack to being fully open.
It is, therefore, the general object of the present invention to provide a lockable butt hinge arrangement for a door which will permit opening of the door to selected degrees of opening but no further.